Skip to main content

Full text of "The Morphology And Evolution Of The Apes And Man"

See other formats


78
ilOEPHOLOGY AND EVOLUTION
tiff. 19, are not as numerous as those in the Gibbons
o
and Chimpanzee, but more numerous and intricate than those in the Gorilla, The papillary ridges form loops on the terminal phalanges, over the head of the second metacarpal bone and on the thenar and hypo-thenar areas, which, however, are not elevated. On the rest of the palm, lines radiate from the carpus to the roots of the fingers. The first and second digits of the fingers have transverse ridges*
The back of the hand is rough, and it is covered with hairs to the distal extremities of the second phalanges of all the digits except the pollex. The hairs on the fingers are short and point distally, but those on the hand are long and directed proximally.
The foot is long and narrow. The digits are arranged as in the hand, and the hallux is diminutive ; it is frequently, but not always, devoid of a nail.  The plantar surface is glabrous, and the arrangement of the flexure lines (fig. 20) shows that the foot is a grasping organ. The dorsum is hairy down to the distal extremities of the penultimate phalanges. So it is evident that the external characters of the hand and foot have much in common.
The umbilicus is situated above the middle of the body as in Man, but it is farther from the symphysis pubis ; in the Chimpanzee it is nearer the middle of the body, but it is below it in the Gorilla.
There are two insignificant pectoral mammse, and even in lactation they are collapsed.
The neck is short, but the laryngeal air-sacs produce balloon-like swellings between the chin and the sternum.
Hair. The whole body, with the exception of the